Just go to the enlistment new pilot page, set the country, set the time, the type of mission (fighter in this case), set the type of plane and hit begin enlistment. It will list all squadrons, one at a time that use the type of plane you want. If it lists a lesser plane, odds are you will get that, so hold out for your plane of choice. It will put you there and then finish the enlistment process the normal way.
A word of warning: If you choose a squadron that is transitioning from one plane to another, as the new kid in the squadron, you will usually get assigned the older plane type. This has happened multiple times to me.
I think I remember seeing that the upcoming 2020 update should fix this behavior, so you get the plane you ask for.